Factor analysis of tongue shapes in the midsagittal plane (supported by qualitative three-dimensional analysis) has identified 2-3 statistical basis functions which are sufficient to represent the shapes of most vowels, and which may be the result of underlying neuromotor coordinative structures. The first aim of the proposed research will be to extend this result by finding statistical basis functions for three-dimensional tongue shapes. The second and third aims of this research will explore the possibility that basis functions may be a speaker-dependent behavior, governed by speaker-independent acoustic constraints: the second aim of the proposed research will be to test for speaker-dependent variation in the basis functions, while the third aim will be to determine whether speaker-dependent variation of the basis functions has a significant effect on vowel format frequencies. All of the tongue shapes in these experiments will be obtained by collecting and segmenting MR images of four speakers (11 vowels, 6 consonants). At the end of the proposed research, MR images will be published on CD-ROM for the benefit of other speech production researchers.